Firearms design involves many non-trivial challenges. Traditionally, semiautomatic handguns have been made with a metal frame that includes the grip. The grip portion defines a magazine well into which a magazine is installed. A slide mounts to and slides longitudinally along rails along the top of the frame as the action is cycled. The frame defines an open region adjacent and above the magazine well for the fire control group. Components of the fire control group are installed in the frame, often with a pin that extends laterally through the frame. More recently, the traditional semiautomatic pistol has been modified to include a polymer grip module that defines a well for a separate metal frame that houses the fire control group. The frame is installed into the grip module above the magazine well and includes rails for the slide. Some such handguns have become popular for their reduced weight and modularity.